raising concrete floor 70mm

[dml]

Hi All

I'm looking to raise the level of a solid concrete utility floor by 75m to match adjacent Kitchen.
i intend to use a sharp sand and cement screed, then my floor layer will latex self level through both rooms prior to laying vinyl flooring.
the DPM is visible around the edge of the floor where it meets the wall my question is can i just screed on top of the existing concrete and to the walls or do i put another DPM on top of existing floor and up the walls?
or is there another suggested method of raising 75mm

Thanks in advance

 

[aveatry]

How old is the floor as I am thinking that there is no insulation in there so you can use PIR insulation to raise the floor by 50mm and maybe 25mm ply on top of that then you have done the job quicker and have an insulated floor to boot

 

[dml]

I'm guessing the utility extension is early 90's and no insulation, i haven't been in the house long and the other rooms appear to be a floating chipboard floor over PIR.
I wanted to avoid timber in the utility as blocked washing machine filters are a regular occurrence and with the best will in the world involve a fair amount of water on the floor!
However you are right it would be quicker and have the advantage of being insulated .
does the PIR lay straight on the concrete or a membrane in between?

 

[catlad]

Lot of things will stick pir insulation, expanding foam being the one I use a lot.
Sounds like you would need to finish it of with Vinyl.

 

[23vc]

Could use T&G ply rather than chipboard. Copes better with getting wet

 

[aveatry]

I wanted to avoid timber in the utility as blocked washing machine filters are a regular occurrence and with the best will in the world involve a fair amount of water on the floor!

If you seal the edge of your vinyl to wall then the water can not get under.
I have tiles and have sealed the perimeter and also under the unit next to the washing machine have siliconed a length of plastic conduit to the floor so that any leaks will show themselves out the front and not spend weeks doing damage out of sight.

 

[noseall]

Hi All

I'm looking to raise the level of a solid concrete utility floor by 75m to match adjacent Kitchen.
i intend to use a sharp sand and cement screed, then my floor layer will latex self level through both rooms prior to laying vinyl flooring.
the DPM is visible around the edge of the floor where it meets the wall my question is can i just screed on top of the existing concrete and to the walls or do i put another DPM on top of existing floor and up the walls?
or is there another suggested method of raising 75mm

Thanks in advance

Yes. Screed would be ideal in a utility. Avoid anything timber or that has permeable layers.

 

[mrrusty]

Avoid anything timber or that has permeable layers

You could use this https://www.cwberry.com/kronobuild-p5-fast-shield-tg-chipboard-flooring-2400-x-600-x-22mm

My experience with it is that although it says "60 days" it is to all intents totally waterproof. I used it for a garden room build and it was totally unaffected by standing water, and an offcut I left outside for a few months, I subsequently used when I was looking for a piece of board for a little job. It hadn't warped, delaminated, or swelled.

As a floating floor over PIR I think it would be ideal

 

[Ivor Windybottom]

I had/have a chipboard floating floor in a shower room. It was all rotten wet mush when I pulled it up. You can't rely on sealant to keep water out, it will find a way in and will never dry out as there's no air circulation.

Floating floors are great for bedrooms and living rooms. But add plumbing and they're a problem. One is that the bounce can cause leaks - supply or waste pipes between the floor and wall get stressed everytime you walk past or the washing machine spins. I know someone whose bath was on one, they found out eventually that the waste pipe was leaking and had filled the entire void with water. Presumably it got compressed when the bath was full, then bounced back up when emptied, breaking the seal on the waste pipe. A massive job, it had seeped outwards into adjoining rooms.

I did replace the one in my shower room, but I did put the shower tray on concrete and put solid timber under the toilet and basin and around the perimeter of the room. There's so much timber I'd have been better off just screeding it really.

I'd say you had the right idea in the first place. For 75mm probably use semi-dry concrete made with 10mm ballast, so you've got gravel to give it some strength. You can get 10mm ballast from most builders merchants in bulk bags, probably not available from Wickes/B&Q though, standard ballast is 20mm which is too chunky. Then the self-levelling screed over the lot.

Don't worry about the damp proof membrane. The floor and walls are both dry, i.e. above the membrane, so you won't be bridging to anything damp.

 

[aveatry]

I had/have a chipboard floating floor in a shower room. It was all rotten wet mush when I pulled it up. You can't rely on sealant to keep water out, it will find a way in and will never dry out as there's no air circulation.

Floating floors are great for bedrooms and living rooms. But add plumbing and they're a problem. One is that the bounce can cause leaks - supply or waste pipes between the floor and wall get stressed everytime you walk past or the washing machine spins. I know someone whose bath was on one, they found out eventually that the waste pipe was leaking and had filled the entire void with water. Presumably it got compressed when the bath was full, then bounced back up when emptied, breaking the seal on the waste pipe. A massive job, it had seeped outwards into adjoining rooms.

I did replace the one in my shower room, but I did put the shower tray on concrete and put solid timber under the toilet and basin and around the perimeter of the room. There's so much timber I'd have been better off just screeding it really.

I'd say you had the right idea in the first place. For 75mm probably use semi-dry concrete made with 10mm ballast, so you've got gravel to give it some strength. You can get 10mm ballast from most builders merchants in bulk bags, probably not available from Wickes/B&Q though, standard ballast is 20mm which is too chunky. Then the self-levelling screed over the lot.

Don't worry about the damp proof membrane. The floor and walls are both dry, i.e. above the membrane, so you won't be bridging to anything damp.

I agree for a shower room 100% but this is a utility room with appliances that may or may not leak at some point.

 

[noseall]

I agree for a shower room 100% but this is a utility room with appliances that may or may not leak at some point.

It's more of the fact that when they do, the water gets trapped between the various layers and becomes an issue. It's difficult then to dry everything out. Screed would be more suitable, but not as thermally efficient.

 

[aveatry]

It's more of the fact that when they do, the water gets trapped between the various layers and becomes an issue. It's difficult then to dry everything out. Screed would be more suitable, but not as thermally efficient.

That's why I suggested to seal the perimeter.
Would 25mm PIR with sand/cement of 50mm be stable enough to then finish of with tiles throughout which would be the best waterproof option.

EDIT - I re read he needs to raise it by only 70 not 75

 

[noseall]

That's why I suggested to seal the perimeter.
Would 25mm PIR with sand/cement of 50mm be stable enough to then finish of with tiles throughout which would be the best waterproof option.

EDIT - I re read he needs to raise it by only 70 not 75

It's a bit lean (45mm) for an unbonded screed.

 

[aveatry]

It's a bit lean (45mm) for an unbonded screed.

Ok so too thin - what about with added chopped fibreglass, I have used it a few times and subsequently had to chisel some and its really strong

 

[noseall]

Ok so too thin - what about with added chopped fibreglass, I have used it a few times and subsequently had to chisel some and its really strong

?

You could add granno chippings, but what's the point. I doubt any of the OP's floors have any insulation.